1. Field of the Invention
The present invention relates to an appearing and disappearing core type writing instrument capable of appearing or disappearing a core of a writing instrument based on rotation.
2. Description of the Background Art
In the conventional art, various kinds of appearing and disappearing core type writing instruments in which a core appears and disappears based on a pushing or rotating operation are known. However, the above-described conventional appearing and disappearing core type writing instruments have a complicated construction, and the fabrication cost is high. In addition, the durability is weak, and the life span is short. Furthermore, there are many elements which are worn out due to friction, so that a desired operation can not be implemented. In addition, it is difficult to handle the conventional appearing and disappearing core type writing instruments.
Accordingly, it is an object of the present invention to provide an appearing and disappearing core type writing instrument which is capable of implementing a simple construction, low fabrication cost and good durability. In addition, it is easy to handle the writing instrument based on the small number of the friction elements.
To achieve the above objects, there is provided an appearing and disappearing type writing instrument which includes a hollow cylindrical body having an opened front end, a driving member which is engaged at an intermediate portion of the body in such a manner that the driving member is not rotated with respect to the body, a hollow cylindrical guide inserted into the front end of the body and rotatably engaged to the body, and a moving rod which is threadedly engaged with the driving member and is forwardly and backwardly moved by the driving member which is integrally rotated with respect to the body for thereby appearing and disappearing the core through a front end portion of the guide in a state that the core is engaged to the front end of the moving rod and is inserted into the guide and is inserted into the non-rotational through hole formed at the rear end of the guide in such a manner that the moving rod is movable in the forward and backward directions.
The guide is rotatable with respect to the body in such a manner that a protrusion and groove formed in parallel along an outer surface of the end portion of the same are inserted into concave and convex portions formed in parallel along an inner surface of the front end of the body.
The driving member is not rotatable with respect to the body in such a manner that a threaded portion formed in an outer surface of the driving member is engaged with a threaded portion formed in an inner surface of the body.
The moving rod is a rod having a rectangular cross section having a threaded portion formed at both side surfaces, and a through hole formed in the rear end of the guide into which the moving rod is inserted is of rectangular shape to correspond with the cross section of the moving rod.